Development of Inhibitory Control in Children With Attention Deficit/Hyperactivity Disorder by the Modified Stop-Signal Task

ADHD is known well as a developmental disorder characterized by behavioral inhibition. The present study aimed to investigate developmental changes and characteristics of inhibitory control in children with ADHD. For this purpose, we used a stop-signal task, modifying the procedure in order to determine the timing of the stop delay so that the timing was related to individual response speed. Participants, elementary-school-age children with ADHD (N=18) and without ADHD (controls; N=64), were divided into 2 groups, younger and older. The children with ADHD had variable reaction time; the rate of their errors was high compared to the control children. Their reactions to go signals were inefficient; there were no differences between the 2 ADHD groups on the inhibition. Some children with ADHD were able to inhibit the response to go signals and used waiting strategies, as did the control children. However, the change in their inhibitory control with increasing age was slow in comparison with the control children. We found that how the strategies were used was related to inhibitory control.